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P Markiewicz

Publications and source records attributed to P Markiewicz.

32 records · Page 2Linked to original sources
PubMed1992

Specific sequences and a hairpin structure in the template strand are required for N4 virion RNA polymerase promoter recognition.

Coliphage N4 virion-encapsidated, DNA-dependent RNA polymerase (vRNAP) is inactive on double-stranded N4 DNA; however, denatured promoter-containing templates are accurately transcribed. We report that all determinants of vRNAP promoter recognition exist in the template strand, indicating that this enzyme is a site-specific, single-stranded DNA-binding protein. We show that conserved sequences and the integrity of inverted repeats present at the promoters are essential for activity, suggesting the necessity for specific secondary structure. Evidence for such a structure is presented. We propose a model for in vivo utilization of vRNAP promoters in which template negative supercoiling yields single-strandedness at the promoter to reveal the determinants of vRNAP binding. This structure is stabilized by the binding of E. coli single-stranded DNA-binding protein to yield an "activated promoter."

Affinity Labels↗
PubMed1992

Escherichia coli single-stranded DNA-binding protein is a supercoiled template-dependent transcriptional activator of N4 virion RNA polymerase.

Coliphage N4 is a double-stranded DNA virus that requires the sequential activity of three different RNA polymerases during infection. The N4 virion RNA polymerase, which is carried in the virion and is injected with the DNA at the start of infection, is responsible for the synthesis of N4 early RNAs. In vitro, the virion RNA polymerase can transcribe double-stranded N4 DNA accurately and efficiently but only when the DNA is denatured. We have shown previously that the activity of DNA gyrase is required for in vivo early N4 transcription. We report here that Escherichia coli single-stranded DNA-binding protein (SSB) is also required for N4 early transcription. In vitro, linear or relaxed templates cannot be activated by SSB; however, supercoiled template and SSB allow the virion polymerase to recognize its promoters on duplex DNA and activate transcription. The effects of supercoiling are limited to transcript initiation and are not required for transcript elongation. The activation is specific for SSB; no other single-stranded DNA-binding proteins can substitute. Therefore, SSB is one of a small number of proteins that function to stimulate both replication and transcription. The basis for the specificity of SSB, the mechanism of transcriptional activation by SSB and template supercoiling, and their role in the N4 transcriptional program during development are discussed.

Base Sequence↗
PubMed1992

[Results of the treatment of idiopathic hydrocephalus by shunt implantation after computerized cisternography].

A retrospective study was reported of 19 patients (10 males and 9 females aged from 11 to 65 years) with idiopathic hydrocephalus treated by shunt implantation after qualification for this treatment based on computed tomocisternography. Clinical improvement was noted in 16 patients (84%), and after 2 months the therapeutic results by Black's scale were good in 13 patients (65%).

Adolescent↗
PubMed1989

[Dopamine beta-hydroxylase activity after subarachnoid hemorrhage].

Dopamine beta-hydroxylase activity was determined in the patients who underwent subarachnoid haemorrhage prior to had following surgery. Dopamine beta-hydroxylase activity was treated as an index of catecholaminergic system activity depending on the incidence and type of vasoconstriction. Dopamine beta-hydroxylase activity in 41 patients treated surgically was compared with the results obtained in 50 control individuals. Changes in the dopamine beta-hydroxylase activity were noted prior to and after surgery depending upon the incidence and type of vasoconstriction. However, the observed differences were statistically insignificant.

Adult↗
PubMed1989

Quality of survival of patients with brain gliomas treated with postoperative CCNU and radiation therapy.

This prospective randomized clinical trial compared the effectiveness of combined treatment with CCNU and radiation therapy to the use of radiation therapy alone for the postoperative management of supratentorial brain gliomas (67% anaplastic) in 198 patients. The results were evaluated with the aid of a specially developed weighted neuropsychological test battery providing single-value estimation of "life quality" of patients, as well as with a clinical performance scale. Based on these methods, it was established that patients improved within 6 months following therapy. This improvement was maintained in surviving patients during the 2-year follow-up period. The patients led a relatively normal life, but when their condition deteriorated their decline was rapid. The median survival time of patients treated with radiotherapy did not differ significantly from that of patients receiving chemotherapy in addition. Nor did the analysis of life quality and of changes in clinical performance show any benefit in supplementing surgery and radiation therapy with CCNU chemotherapy at the dosage used.

Adolescent↗
PubMed1988

N4 virion DNA dependent-RNA polymerase: initiation sequences utilized by the enzyme on heterologous templates.

Bacteriophage N4 virion-encapsulated RNA polymerase, the enzyme responsible for transcription of the phage early RNAs, is unable to use duplex linear DNA as a template. In contrast to other RNA polymerases, the enzyme transcribes denatured N4 DNA with in vivo specificity. The promoter sequences for three sites of transcription initiation on the N4 genome have been determined and found to contain conserved sequences and two sets of inverted repeats. In order to define the minimal sequence requirements for N4 virion RNA polymerase activity, we have screened several heterologous DNAs, amounting to 64,328 bases, for their ability to support transcription. Several sequences allowing specific initiation were found. Their location, properties and the relation to N4 virion RNA polymerase promoters are discussed.

Coliphages↗
PubMedDate not supplied

[The influence of radiation doses on the results of radiosurgery of brain arteriovenous malformations].

Stereotactic radiosurgery as a method of treatment of inoperable brain angiomas has been in use in the Neurosurgery Department, Medical Academy in Lublin since 1990. The patients receive radiation from a Neptune 10P linear accelerator of 9 MeV photon energy (X radiation). The Laitinen stereoadapter used by us makes possible precise targeting and radiation application in time suitable for the patient and the whole treatment team. This frame produces no disturbances of CT image and is not covering the target. Non-invasive head immobilization in the frame is highly stable, although it requires good communication with the patient and his full cooperation. The purpose of the study was a comparison of the results of radiosurgery applied in the treatment of inoperable brain angiomas of various size with radiation doses 4000 cGy and 3000 cGy. The material comprises 40 first cases out of over 120 patients treated in this way for inoperable angiomas. The first group of 20 patients received 4000 cGy and the second group of 20 patients received 3000 cGy doses. Complete obliteration of angiomas was achieved in 16 (80%) cases treated with the 4000 cGy dose, and in 17 (85%) cases treated with the 3000 cGy dose. Late postradiation reactions developed in 15 (75%) patients in the first group with permanent changes in 5 (25%) patients. In the second group late postradiation reactions developed in only 6 (30%) cases and regressed in all. Treatment effectiveness (complete obliteration) after doses of 3000 and 4000 cGy was similar, and it decreased with greater size of angiomas. The per cent of postradiation complications after lower doses was much smaller, and permanent neurological changes were seen only after higher doses. The obtained results of the method are comparable with those of the authors using invasive methods of fixation of stereotactic frames.

Adolescent↗
PubMedDate not supplied

[Level of dopamine beta-hydroxylase activity in subarachnoid hemorrhage treated conservatively and surgically].

The activity of the catecholaminergic system was studied by analysis of changes in the activity of dopamine beta-hydroxylase (DBH) in patients after subarachnoid haemorrhage treated conservatively or surgically. The activity of DBH was analysed in a group of 20 conservatively treated patients and 41 treated surgically, with comparison to 50 controls. DBH activity was determined on days 1-3 after subarachnoid haemorrhage, in the second week, and before and after operation. In the period of the investigations changes were noted in DBH activity depending on the clinical state of the patients, and no direct effect of the operation was noted on DBH activity in the serum.

Adult↗
PubMedDate not supplied

[Vasoactive neuropeptides CGRP (calcitonin gene-related peptide) and vasospasm during subarachnoid hemorrhage from ruptured intracranial aneurysm].

The authors discuss the role of active neuropeptides Calcitonin Gene-Related Peptide (CGRP) and Vasoactive Intestinal Polypeptide (VIP) in the arterial spasm caused by haemorrhage from ruptured intracranial aneurysm. These substances act as vasodilators on brain vessels. Between the first and the second week after subarachnoid haemorrhage their concentration in the periarterial nerve fibres of the big vessels is significantly low. According to the experiments, the erythrocytes are this component of the blood which causes the decrease of the number of nerve fibres containing CGRP and VIP. The clinical tests of CGRP and VIP in the treatment of the vascular spasm after subarachnoid haemorrhage are being continued.

Aortic Dissection↗
PubMedDate not supplied

[Familial occurrence of intracranial aneurysms].

Four cases of intracranial aneurysms are reported found in two families. They accounted for 1% of all patients with these aneurysms treated in that time period. The aetiology of the aneurysms, the most frequent locations in familial cases and the risk of occurrence of asymptomatic aneurysms in such families are discussed.

Adult↗
PubMedDate not supplied

[Spontaneous intracerebral hematomas in the material of the Department of Neurosurgery of Medical Academy in Lublin].

Between 1972 and 1991, 170 patients with spontaneous nontraumatic intracerebral haematomas were treated in the Neurosurgical Department of Medical Academy in Lublin. In 89 (52.5%) patients, the haematomas were caused by ruptured aneurysms; in 14 (8%), by angiomas; 67 (39.5%) haematomas had other etiology. Within the latter group of patients, 27% suffered from hypertension. Hypertension was also found in 15% of the patients with aneurysms and in 7% of the ones with angiomas. 34% of the haematomas were localized in the temporal lobe, 28%-in the frontal lobe, 3%-in parital lobe, 2%-in occipital lobe, 23% of haematomas were multi-lobal, 8% were found in deep brain structures, and in 2% haematomas were found in cerebellum. 128 patients underwent operative treatment, with a mortality rate of 26%, while 42 patients were treated conservatively, with a mortality rate of 19%. Basing on this material, the authors discuss indications for operative treatment of the haematomas.

Adult↗